Yasuo Horii* and Nobutoshi Tanaka**

* KUBOTA Corporation, Water and Sewage Plant Engineering Department
** Hokkaido Univ., Faculty of Eng.

+ Correspondence should be addressed to Nobutoshi Tanaka:
(N13, W8, Kita-ku, Sapporo 060 Japan)

Abstract

These days in Japan, solid waste disposed of in municipal sanitary landfills has shifted from biodegradable refuse to incinerator residue and incombustibles. In addition, the content of soluble calcium and chloride in the incinerator residue is becoming higher and higher. Consequently in leachate treatment plants, problems of calcium scale and erosion by salt are occurring. In a limited situation, damage to agriculture resulting from the high concentration salt in effluent from treatment plants is feared. This paper presents the current situation, including damage and countermeasures taken, regarding the high concentration of calcium and chloride ion in leachate treatment plants. In addition, treatability of dioxins in leachate treatment plants and the development of dioxins decomposition method utilizing ozone and ultraviolet light are presented.

Key words: sanitary landfills, incinerator residue, calsium, chloride ion, dioxins